The present invention relates generally to mobile communication devices such as mobile telephones and the like, and more specifically to a holder for a mobile communication device, in particular, a mobile telephone, having a receptacle capable of reducing the Specific Absorption Rate (SAR) of the mobile communication device.
It is known that exposure to very high levels of radio frequency electromagnetic energy, particularly at microwave frequencies, can heat biological tissue causing harm by increasing body temperature, disrupting behavior, and damaging biological tissue. Consequently, the effect of low levels of radio frequency energy, such as produced by mobile telephones, on human tissue has also come under intense scientific investigation. While there is no scientific proof that the relatively low levels of radio frequency energy produced by mobile telephones can cause damage to human tissue, many governmental bodies, such as the United States Federal Communication Commission (FCC) and many European regulatory organizations, have nevertheless imposed precautionary regulations and measurement guidelines aimed at limiting the exposure of users to such energy.
Accordingly, methods and systems of reducing exposure to low level radio frequency energy for mobile telephones have been developed. Specific absorption rate (SAR) is a widely accepted measurement of radio frequency energy absorbed into the body in watts per kilogram (W/kg) averaged over a certain amount of tissue when the telephone is situated close to the human body.
Existing concepts used for reducing the SAR value of a mobile telephone are based on three ideas: adding reflective shielding to the mobile telephone, creating distance between the antenna of the telephone and the human body, and reducing the radiated power of the telephone through incorporation of absorbing materials within the telephone's housing. A problem associated with reducing the SAR value of a mobile telephone is mostly a parallel reduction in performance of the mobile telephone. For example, absorbing devices reduce the available radiated energy of the telephone but limit the area in which the mobile telephone may be used (i.e., reduce the coverage area of the telephone).
As consumers'reliance upon mobile and cellular communication has increased, individuals regularly carry mobile telephones on their bodies by use of a mobile telephone holder having a receptacle such as a pouch, case, or holster. A benefit of a mobile telephone receptacle is the reduction of SAR value of the mobile telephone when secured within the mobile telephone receptacle. However, mobile telephone receptacles known to the art are of a homogeneous material, and radiating elements of the mobile telephone are thus attenuated equally. A drawback associated with equally attenuating the radiating elements of a mobile telephone is the unnecessary reduction in performance of the telephone.
Consequently, there is a general need for a mobile telephone holder having a receptacle for reducing the SAR value of a mobile telephone secured within the receptacle, while limiting the performance loss of the mobile telephone associated with the reduction of the SAR value of the mobile telephone.